February 2009 Plant of the Month — Yucca!

 

Submitted by Matthew Morrow

Although thoughts of spring are creeping into all of our minds, let’s not get ahead of ourselves seasonally. A plant with superb winter interest may sound like a killjoy, but yucca looks great year round.

Yucca may be a plant that you’ve seen sitting forlornly on the property of an older relative, full of weeds and looking just plain ornery. Though some can be ornery, especially with small children, many have soft leaves and are anything but plain. For bold, eye-catching architecture in your garden, they can’t be beaten.

Members of the Agavaceae family, yuccas tolerate a variety of soils from alkaline to acidic, sandy to loamy, anything but wet. They love full sun, but can grow and thrive in partial shade as well. The flower stalks on yucca can be quite impressive, and in mid-summer (later in cooler areas) they thrust skyward to anywhere between 3 and 6 feet tall with pendulous, tulip-shaped white blooms that hold for weeks. Many people are surprised to learn that many of these South Western U.S. natives are quite hardy….some to zone 5 and even zone 4 in protected sites. Slow growing, most reach to between 2 and 4 feet, but a few species are trunk forming and can grow to about 12 feet.

Many of the trunk-forming varieties are hardy to zone 7, including Yucca elata (Soap Tree) and Yucca scotti. Yucca rostrata is the real beauty of this bunch, and it is hardy to zone 5b. A native of Mexico, Y. rostrata is an elegant and hardy blue-leaved yucca that can eventually grow to be 10 feet. It will grow a bit faster in alkaline soil. This branch-forming yucca boasts leaves that are more user friendly according to Tony Avent of Plant Delights Nursery. By that I think he means that they are less likely to poke your eye out. ‘Sapphire Skies’ is a cultivar with magnificently slender, powder blue foliage.

Yucca filamentosa is a non-trunk-forming variety, commonly called Adam’s Needle. It shows exceptional cold hardiness and is rated as zone 5. This species has rough, thick leaves whose margins are covered with a fine, thread-like filament. Some cultivars include ‘Bright Edge’, ‘Garland Gold’ and ‘Golden Sword’. ‘Golden Sword’ is a personal favorite, and it is a pleasure to see the bright yellow- centered leaves radiating upwards. These yellow margins really pop in winter, and look almost like you can spread them on toast. Last but not least is ‘Color Guard’, a fabulous variegated cultivar that shines in any garden and turns shades of pink and coral in the colder months.

An interesting species is Yucca recurvifolia, and from it was produced ‘Margaritaville’ and ‘Banana Split’. These cultivars both have a weeping habit and add a graceful touch to the garden. ‘Margaritaville’ has creamy white and green variegation, while ‘Banana Split’ has an intense yellow-centered leaf. Both are zone 7 to 9. Y. recurvifolia can be especially prone to spotting its roots linger amongst too much moisture in the winter, so remember to supply a properly draining soil. Y. recurvifolia eventually forms a trunk and may come to resemble a smallish palm, in which case you can dig it up and start again if the look offends your eye.

Spanish Dagger is the common name for a particularly wicked plant, Yucca gloriosa. Like many wicked things, Y. gloriosa, especially cultivar ‘Variegata’, is also beautiful. Be very cautious around this plant. The leaves can impale a lumberjack. It is listed as zone 7. Yucca aloifolia, also decidedly wicked, is hardy to zone 6, but dislikes too many consecutive days at or below 0 degrees. Y. aloifolia ‘Variegata’ has a bi-color margin of light green, edged with creamy white, and culminating in a very pointy leaf.

So, you can see there are many options available to yucca enthusiasts, as well as neophytes. Plant a few and see if their usefulness and beauty pierce your heart like Cupid’s arrow…just have some bandages ready.

Matthew Morrow is a member of the Horticulture Team at University of Tennessee’s West Tennessee AgResearch and Education Center in Jackson.

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Contact:

Matthew Morrow, West Tennessee AgResearch and Education Center,
(731) 424-1643

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The following yuccas can be found at the UT Gardens in Jackson:

Y. aloifolia ‘Variegata’
Y. filimentosa ‘Bright Edge’ ‘Color Guard’ ‘Gold Sword’
Y. gloriosa ‘Variegata’
Y. recurvifolia ‘Margaritaville’ ‘Gold Ribbons’
Y. rostrata ‘Sapphire Skies’
Y. filimentosa ‘Color Guard’ and ‘Bright Edge’ can also be seen at the UT Gardens in Knoxville.

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